Principle
Rather than quantizing the absolute value of the input analog waveform, delta modulation quantizes the difference between the current and the previous step, as shown in the block diagram in Fig. 1.
The modulator is made by a quantizer which converts the difference between the input signal and the average of the previous steps. In its simplest form, the quantizer can be realized with a comparator referenced to 0 (two levels quantizer), whose output is 1 or 0 if the input signal is positive or negative. It is also a bit-quantizer as it quantizes only a bit at a time. The demodulator is simply an integrator (like the one in the feedback loop) whose output rises or falls with each 1 or 0 received. The integrator itself constitutes a low-pass filter.
Read more about this topic: Delta Modulation
Famous quotes containing the word principle:
“I do not mean to exclude altogether the idea of patriotism. I know it exists, and I know it has done much in the present contest. But I will venture to assert, that a great and lasting war can never be supported on this principle alone. It must be aided by a prospect of interest, or some reward.”
—George Washington (17321799)
“Now, what I want is, Facts. Teach these boys and girls nothing but Facts. Facts alone are wanted in life. Plant nothing else, and root out everything else. You can only form the minds of reasoning animals upon Facts: nothing else will ever be of any service to them. This is the principle on which I bring up my own children, and this is the principle on which I bring up these children. Stick to Facts, sir!”
—Charles Dickens (18121870)
“Whether our feet are compressed in iron shoes, our faces hidden with veils and masks; whether yoked with cows to draw the plow through its furrows, or classed with idiots, lunatics and criminals in the laws and constitutions of the State, the principle is the same; for the humiliations of the spirit are as real as the visible badges of servitude.”
—Elizabeth Cady Stanton (18151902)